Inner tube for tires



M. RAsMussr-:N

'INNER -TUBE FOR TIRES Filed April 2l, 19212 Marfil? asmsserz.

Patented May 1.3, i924.

sT-Es i MARTIN RASMUSSEN, OFv RACINE, WISCONSIN.

INNER TUBE FOR TIRES'.

.application filed April 21, 1922. Serial No. 555,900. i

To all whom t may canberra'.

Be it known that I, MARTIN RAsMUssEN,

Aa citizen of the UnitedStates, and a resident of Racine. in the' ycountyof Racine and vState of VViscciisin, have invented certain new and useful Improvements in Inner Tubes for Tires; and I do hereby declare that the following is a full, clear. and exact description thereof, reference being had to the accompanying drawings, and to the characters of reference marked thereon, which forma part of this specification.

This inventionl relates to improvements iii inner tubes for pneumatic tires, and refers more specifically to a form of inner tube that is so constructed as to increase its durability, and to avoid blow outs, and

pinching of inner tube in a manner to rup- I ture the same. n s

An inner tube embodying my invention embraces an inelastic or non-stretchable tube which is provided in its wall with one or more depressions of flute like formation formed by forcing'inwardly the material of the tube to produce a rib or ribs internally of the tube and a depression or depressions externally of the tube. Thereafter when air under pressure is forced into the tube the material of the tube wall is displaced, by reason of said finte-like formations so as to expand the tube against the wall ofthe casing Ito produce the desired pneumatic effect, without, however, stretching the tube.

The wall of the inner tube is made of a material possessing considerable tensile strength to withstand high internal pressure without rupturing the tube wall, and the wall is of such thickness as to avoid pinching or chaling of the tube wall, and such, also as to avoid protrusion of the tube wall through puncture openings in the casing wall. Preferably the structure of the tube is such that in the parts thereof which are subject to the greatest fleXure in the use of the tire, or at the sides of the tube, are

well disposed to withstand such flexurewithout destructive effect on the inner tube.

In the drawings, showing two embodiments of my invention:

Figure 1 is a cross section of a tire equipped with a tube made in accordance with. my invention, showing the tube inflated.

Figure 2 is a cross section of thedeflated inner tube. v

Figure 3 is a side elevation of the inner tube.;

Figure 4 is a modified form of the inner tube.

As shownin said drawings, 1() designates the outer casing or shoe of the tire, and 11 designates the inner tube. Said inner tube is shown as being made of one or more layf ers of suitable material, such as rubberized canvas, there being at least one layer at the sides of the tube, and preferably there are added layers at the tread portion to resist puncture, and the inner'porti'on of the tube may be thickened by the addition of a layer' or layers through which the shank of the r air valve`12 extends.

The inner tube is made of an outer layer or layers 14 of rubberized canvas or the like and aninner layer 15 of a non-heat conductingmaterial, such as asbestos cloth. The tube is'first made of cylindric crosssection, oversize with respect to the casing with which it is to `be used. Thereafter the s tube is placed over a suitable form, constituting part of a vulcanizing machine. Said form has annular grooves or depressions at its opposite sides, and the material of the oversize tube is forced into these depressions by wedge cross-section ring members constituting also parts of said vulcanizing niachine. The parts thus assembled are held in position during the vulcanizing operation. After vulcanization the walls of the iiute like depression are permanently fixed or set relatively to the other parts of the tube wall, as shown in Figure 2, the inner narrowest parts of the depressions constituting hinges to accommodate radial deformation of the tube in use.

The inner tube thus formed is placed in the outer casing in theusual manner of fitting an inner tube to the casing and after the parts have been assembled and air under pressure has been admitted to the inner tube through the valve 12, the wall of the said tube is displaced, owing to the presence of, and including the, flute-like depression 17, so as to cause the inner tube to bear against and support all parts of the outer casing, except those portions of the latter that lie directly opposite the outwardly opening depressions on the outer sides ofy said tube, due to said flute-like formations.

It will be readily seen from an inspection of Figure 1 that those portions of the tire which are repeatedly flexed in action is opposite toj the {inte-like formations, so that said flexion of the tire as a whole, incudingf the outer casing and the tube does not impose severe flexing stresses on the inner tube in a iuanner tending to rupture the same. 'It 1vill also be observed in the structure shown in Figure l. even should the outer casing' become broken or punctured, the thickness ot the inner tube is such as to avoid its bulging through the broken casing'. and also that the strength of the inner tube is such as to hold its pressure Therefore, with the use olf my improved inner tube the tire may be continued in use with a considerable or substantial breaking of the wall ot the casingand until the casing is Worn so. as to be practically unfit for further use.

.la Figure #i is shown a construction wherein a single flute-like depression 17 is employed at the radially inner side ot the tube, and this iute-ile depression may be made ot su'tlicient size to receive the shank of the air valve. In this event the expanded inner tube will lie continuouslyagainst the inner Wall oiC the casing except at the radially inner portion thereof.

In both forms o' construction the Wall ofY the inner tube at the outer side thereof is preferablyy 'formed with a `:rreater number of layers than at its sides, and in the construction shown in Figure '1. said Walls of the inner tube ma7 be made with an additional layer or layers at its radially inner side to strengthen the tube at this place. Then adapting` the tubeto a standard Casing the casing may be Worn down to a greater extent than with the usey of an ordinary rubber innertube. For the same reason an outer casing of 'substantially less dimension and Weight can be used7 While producin;lv a tire structure ot great durability asrompared to present standard tire constructions. it will be understood that the said inner tube may be made of other material than those suggested, provided the resistance against blow and rupture and pinching` oit the present tube is not impaired. lt will also be understood that the terms flute-like depressions is not intended to be iimitinn as to a particular manner ot rendering; the inclosed tube expansible7 but other confierurations ot the tube Wall may be employed.

I claim as my invention:

l. An inner tube for a pneumatic tire made of non-stretchable material and provided With one or more circumferential tinte-like formations produced by forcing the Wall of the tube inwardly7 and adapted to lie out o1" contact With a tire casing When the tube is operably inflated.

2. An inner tube and casing for a pneu- -matie tire. said tube being: enclosed Within the casing; and made ot non-stretchable material and provided at its laterally opposite sides. when the tube is operably inflated, with iinvardlv extending, V-shaped7 utelike fornlations. the inner parts of Which constitute hinges about which the tube tienes under radial deformation.

In Witness whereof l claim the foregoing as mv invention. I hereunto append my signature this 19th day of April, 1922.

MARTIN RASMUSSEN. 

